$green = #02a774
$yellow = #F5A100
$bc = #e4e4e4
//一 像 素 下 边 框 
bottom-border-1px($color) 
  position: relative 
  border: none 
  &::after 
    content: '' 
    position: absolute 
    left: 0 
    bottom: 0 
    width: 100% 
    height: 1px
    background: $color
    // transform: scaleY(0.5)
//一像素上边框
top-border-1px($color)
  position: relative
  &::before
    content: ''
    position: absolute
    z-index: 99
    left: 0
    right: 0
    width: 100%
    height: 1px
    background-color: $color
//根据像素比缩放1px像素边框
@media only screen and (-webkit-device-pixel-ratio: 2 ) 
  .border-1px
    &::before
      transform: scaleY(0.5)

@media only screen and (-webkit-device-pixel-ratio: 3 ) 
  .border-1px
    &::before
      transform: scaleY(.333333)

//根据像素比来使用 2x图 3x图
bg-image($url)
  background-image: url($url + "@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
    background-image: url($url + "@3x.png")

//清除浮动
clearFix()
  *zoom: 1
  &::after
    content: ''
    display: block
    clear: both
    